147 research outputs found

    Repair of ovine peripheral nerve injuries with xenogeneic human acellular sciatic nerves prerecellularized with allogeneic Schwann-like cells‚ÄĒan innovative and promising approach

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    Introduction: The iatrogenic effects of repairing peripheral nerve injuries (PNIs) with autografts (AGTs) encouraged the present study to involve a new approach consisting of grafting xenogeneic prerecellularized allogeneic cells instead of AGTs. Methods: We compared sheep's AGT regenerative and functional capacity with decellularized human nerves prerecellularized with allogeneic Schwann-like cell xenografts (onwards called xenografts). Mesenchymal stem cells were isolated from ovine adipose tissue and induced in vitro to differentiate into Schwann-like cells (SLCs). Xenografts were grafted in ovine sciatic nerves. Left sciatic nerves (20 mm) were excised from 10 sheep. Then, five sheep were grafted with 20 mm xenografts, and five were reimplanted with their nerve segment rotated 180¬į (AGT). Results: All sheep treated with xenografts or AGT progressively recovered the strength, movement, and coordination of their intervened limb, which was still partial when the study was finished at sixth month postsurgery. At this time, numerous intrafascicular axons were observed in the distal and proximal graft extremes of both xenografts or AGTs, and submaximal nerve electrical conduction was observed. The xenografts and AGT-affected muscles appeared partially stunted. Conclusions: Xenografts and AGT were equally efficacious in starting PNI repair and justified further studies using longer observation times. The hallmarks from this study are that human xenogeneic acellular scaffolds were recellularized with allogenic SCL and were not rejected by the nonhuman receptors but were also as functional as AGT within a relatively short time postsurgery. Thus, this innovative approach promises to be more practical and accessible than AGT or allogenic allografts and safer than AGT for PNI repair

    Structural basis for DNA damage-induced phosphoregulation of MDM2 RING domain

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    Phosphorylation of MDM2 by ATM upon DNA damage is an important mechanism for deregulating MDM2, thereby leading to p53 activation. ATM phosphorylates multiple residues near the RING domain of MDM2, but the underlying molecular basis for deregulation remains elusive. Here we show that Ser429 phosphorylation selectively enhances the ubiquitin ligase activity of MDM2 homodimer but not MDM2-MDMX heterodimer. A crystal structure of phospho-Ser429 (pS429)-MDM2 bound to E2‚Äďubiquitin reveals a unique 310-helical feature present in MDM2 homodimer that allows pS429 to stabilize the closed E2‚Äďubiquitin conformation and thereby enhancing ubiquitin transfer. In cells Ser429 phosphorylation increases MDM2 autoubiquitination and degradation upon DNA damage, whereas S429A substitution protects MDM2 from auto-degradation. Our results demonstrate that Ser429 phosphorylation serves as a switch to boost the activity of MDM2 homodimer and promote its self-destruction to enable rapid p53 stabilization and resolve a long-standing controversy surrounding MDM2 auto-degradation in response to DNA damage

    Production of biologically active human lymphotactin (XCL1) by Lactococcus lactis

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    Abstract Lymphotactin-XCL1 is a chemokine produced mainly by activated CD8? T-cells and directs migration of CD4? and CD8? lymphocytes and natural killer (NK) cells. We expressed human lymphotactin (LTN) by the lactic-acid bacterium Lactococcus lactis. Biological activity of LTN was confirmed by chemo-attraction of human T-cells by chemotaxis demonstrating, for the first time, how this chemokine secreted by a food-grade prokaryote retains biological activity and chemoattracts T lymphocytes. This strain thus represents a feasible well-tolerated vector to deliver active LTN at a mucosal level

    Temozolomide Enhances Triple-Negative Breast Cancer Virotherapy In Vitro

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    Triple-negative breast cancer (TNBC) is one of the most aggressive types of cancer, and treatment is limited to chemotherapy and radiation. Oncolytic virotherapy may be a promising approach to treat TNBC. However, oncolytic adenovirus (OAd)-based mono-therapeutic clinical trials have resulted in modest outcomes. The OAd potency could be increased by chemotherapy-induced autophagy, an intracellular degradation system that delivers cytoplasmic constituents to the lysosome. In this study, the ability of alkylating agent temozolomide (TMZ)-induced autophagy to increase OAd replication and oncolysis in TNBC cells was evaluated. Human TNBC MDA-MB-231 and HCC1937 cells and mouse 4T1 cells were infected with an OAd expressing the red fluorescent protein mCherry on the virus capsid (OAdmCherry) alone or in combination with TMZ. TNBC cells treated with OAdmCherry/TMZ displayed greater mCherry and adenovirus (Ad) early region 1A (E1A) expression and enhanced cancer-cell killing compared to OAdmCherry or TMZ alone. The combined therapy-mediated cell death was associated with virus replication and accumulation of the autophagy marker light chain 3 (LC3)-II. Overall, this study provides experimental evidence of TMZ’s ability to increase oncolytic virotherapy in both human and murine TNBC cells

    Novel insights into mesothelioma biology and implications for therapy.

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    Malignant mesothelioma is a universally lethal cancer that is increasing in incidence worldwide. There is a dearth of effective therapies, with only one treatment (pemetrexed and cisplatin combination chemotherapy) approved in the past 13 years. However, the past 5 years have witnessed an exponential growth in our understanding of mesothelioma pathobiology, which is set to revolutionize therapeutic strategies. From a genomic standpoint, mesothelioma is characterized by a preponderance of tumour suppressor alterations, for which novel therapies are currently in development. Other promising antitumour agents include inhibitors against angiogenesis, mesothelin and immune checkpoints, which are at various phases of clinical trial testing

    Structural analysis of MDM2 RING separates degradation from regulation of p53 transcription activity

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    MDM2‚ÄďMDMX complexes bind the p53 tumor-suppressor protein, inhibiting p53's transcriptional activity and targeting p53 for proteasomal degradation. Inhibitors that disrupt binding between p53 and MDM2 efficiently activate a p53 response, but their use in the treatment of cancers that retain wild-type p53 may be limited by on-target toxicities due to p53 activation in normal tissue. Guided by a novel crystal structure of the MDM2‚ÄďMDMX‚ÄďE2(UbcH5B)‚Äďubiquitin complex, we designed MDM2 mutants that prevent E2‚Äďubiquitin binding without altering the RING-domain structure. These mutants lack MDM2's E3 activity but retain the ability to limit p53‚Ä≤s transcriptional activity and allow cell proliferation. Cells expressing these mutants respond more quickly to cellular stress than cells expressing wild-type MDM2, but basal p53 control is maintained. Targeting the MDM2 E3-ligase activity could therefore widen the therapeutic window of p53 activation in tumors

    A modified chemical protocol of decellularization of rat sciatic nerve and its recellularization with mesenchymal differentiated Schwann-Like cells: Morphological and functional assessments

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    The functional reconstruction of large neural defects usually requires the use of peripheral nerve autografts, though these have certain limitations. As a result, interest in new alternatives for autograft development has risen. The acellular peripheral nerve graft is an alternative for peripheral nerve injury repair, but to date there is not a standardized chemical decellularization method widely accepted. The objective of this study was to propose a modified chemical protocol of decellularization of rat sciatic nerve and its recellularization in vitro with mesenchymal differentiated Schwann-like cells. After the transplantation, an evaluation of its regeneration was performed using morphological and functional tests. The study consisted of two phases; in phase 1, different concentrations and times of exposure of rat sciatic nerves to detergents were tested, to establish a modified chemical protocol for nerve decellularization. The chemical treatment with 3% triton X-100 and 4% sodium deoxycholate for 15 days allowed a complete decellularization whilst conserving the extracellular matrix of the harvested nerve. In phase 2, the decellularized and recellularized alografts were compared against autografts. The morphological analysis showed a higher positivity to specific myelin antibodies in the recellularized group compared to the autograft. There were no differences in this parameter between the control limb and the experimental limb (recellularized group). The functional analysis showed no statistical differences at week 15 in the Sciatic Function Index in the autograft group vs the other groups. This study sets the morphological and functional bases for posterior studies about nerve defects regeneration in humans

    Histopathological alterations in the striatum caused by Karwinskia humboldtiana (Buckthorn) fruit in an experimental model of peripheral neuropathy

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    The accidental ingestion of Karwinskia humboldtiana (Kh) fruit in humans and animals causes chronic or acute intoxication. Acute poisoning induces respiratory failure that progresses rapidly to death. Studies in animals intoxicated with Kh describe lesions in cerebral cortex, cerebellum, spinal cord, hippocampus and caudate nucleus. Kh intoxication in Wistar rats models the sub-lethal clinical phase observed in humans. Considering these reports, the present study analyzed the histopathological alterations within the striatum following experimental Kh intoxication. Twenty Wistar rats were divided into three groups (n=5) and were intoxicated with Kh fruit. A control group (n=5) was included. Animals were euthanized at several time points (48, 58 and 170 days post-intoxication). The brain was collected, divided and processed for conventional histology or electron microscopy. Sections were stained with hematoxylin and eosin, cresyl violet, Kl√ľverBarrera, and toluidine blue. Immunolabeling was performed for glial cells in the striatum, and the samples were analyzed with light microscopy. Morphometric and statistical analyses were performed. In control group, neurons, axon bundles and neuropil had a normal appearance. At 48 days, hyperchromic neurons with apparent decreased size were observed interspersed among the normal neurons. At 58 days, we observed an increased number of hyperchromic neurons and disorganization of the myelin sheath and neuropil. At 170 days, these alterations persisted in the paralysis group. In treated groups, we observed signs of gliosis and increased axonal diameters. This study is the first report that describes the histopathological alterations within the striatum caused by chronic intoxication with Kh fruit in the Wistar ra

    ESICM LIVES 2016: part three: Milan, Italy. 1‚Äď5 October 2016

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